Secondary Cell Separator Coating for Heat Shrinkage Resistance
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Solution Overview
Problem
Secondary cell separators face issues with heat resistance, leading to potential short circuits between the positive and negative electrodes due to shape changes caused by heat shrinkage.
Innovation Solution
A secondary cell separator coating material comprising a resin made from a modified methylolmelamine condensation resin with an acid group and polyvinyl alcohol, which provides excellent heat resistance and ion permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyolefin porous film is used as a separator, then it provides basic separation function, but it exhibits heat shrinkage causing shape changes and potential short circuits
Solution Approach 1:
The patent applies composite materials by combining polyolefin porous film with a coating layer containing modified methylolmelamine condensation resin and polyvinyl alcohol. This composite structure provides both the separation function of the polyolefin base and the heat resistance of the coating layer, preventing heat shrinkage and shape changes while maintaining reliability.
Solution Approach 2:
The patent changes the chemical composition parameters of the coating layer by using modified methylolmelamine condensation resin with specific acid groups (sulfonic acid, carboxylic acid, or phosphoric acid) and polyvinyl alcohol in controlled ratios. This parameter optimization ensures the coating layer achieves sufficient heat resistance without causing shape changes to the separator.
2Reliability
If a coating layer is formed on the separator surface, then heat resistance is improved, but ion permeability may be reduced
Solution Approach 1:
The patent applies porous materials by forming a coating layer with controlled porosity that allows ion transport. The modified methylolmelamine condensation resin and polyvinyl alcohol create a porous network structure that provides heat resistance while maintaining ion permeability, preventing the trade-off between these two properties.
Solution Approach 2:
The patent applies local quality by creating a coating layer with specific local properties - the coating provides heat resistance where needed on the separator surface while maintaining porosity and chemical composition that allow ion passage. The acid groups in the resin provide localized functional properties that enhance both heat resistance and ion interaction.
3Ease of manufacture
If a coating material containing water-soluble polymer and inorganic filler is used, then coating formation is achieved, but heat resistance and ion permeability are insufficient
Solution Approach 1:
The patent changes the chemical composition parameters from conventional water-soluble polymers to modified methylolmelamine condensation resin with specific acid groups. This parameter change provides sufficient heat resistance while maintaining coating formability through the resin's chemical properties and controlled composition ratios with polyvinyl alcohol.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The coating material enhances the heat resistance and ion permeability of the separator, preventing short circuits and ensuring efficient ion transfer.
Implementation Method 1
a resin being a reaction product of a modified methylolmelamine condensation resin having an acid group and polyvinyl alcohol, or the modified methylolmelamine condensation resin having the acid group and the polyvinyl alcohol
Data Source
AI summary
An ingredient for a secondary cell separator coating material includes a resin which is a reaction product of a modified methylolmelamine condensation resin having an acid group and polyvinyl alcohol, or the modified methylolmelamine condensation resin having the acid group and the polyvinyl alcohol.